diff --git a/passerelle/apps/astech/models.py b/passerelle/apps/astech/models.py
index f2ff939c..31df5fa6 100644
--- a/passerelle/apps/astech/models.py
+++ b/passerelle/apps/astech/models.py
@@ -305,6 +305,8 @@ class ASTech(BaseResource, HTTPResource):
             'designation': True,
         }
         companies = self.call('apicli/rule-call-by-alias/societes_demandeur/invoke', json=payload)
+        if not isinstance(companies, dict):
+            raise APIError('Invalid response: %s' % companies)
         companies = [{'id': str(key), 'text': value} for key, value in companies.items()]
         companies.sort(key=lambda item: item['id'])  # "same as output" sort
         return {'data': companies}
diff --git a/tests/test_astech.py b/tests/test_astech.py
index 7cd2a5eb..c9f661ec 100644
--- a/tests/test_astech.py
+++ b/tests/test_astech.py
@@ -204,6 +204,11 @@ def test_companies(mocked_auth, mocked_request, app, setup):
         {"id": "11", "text": "11 / PLOMBERIE"},
     ]
 
+    mocked_request.return_value = tests.utils.FakedResponse(content="[]", status_code=200)
+    response = app.get(endpoint)
+    assert response.json['err'] == 1
+    assert response.json['err_desc'] == 'Invalid response: []'
+
 
 @mock.patch("passerelle.utils.Request.request")
 @mock.patch("passerelle.apps.astech.models.ASTech.get_authorization")